Everything you need to know about lice in this super thorough FAQ section.

What are lice?​​

Lice are tiny, wingless parasitic insects that live on the hair of humans and feed on small amounts of blood from our scalp. A single adult is called a louse. A baby is called a nymph and they go through three stages before reaching adulthood. A lice egg hatched and unhatched is often called a nit. The medical term for head lice infestation is Pediculosis. There is a common misconception that eggs are white. In fact, an egg is usually pale yellow or caramel in color. A newly hatched nymph is translucent but turns reddish-brown as it consumes your blood.

Where do head lice come from?

Head lice are named for where they live and feed: the human head. They have been annoying people for thousands of years. Nits have even been found on the hair of a 10,000 year old mummy in Brazil. Nit combs have been found dating back 7,000 years ago.

What is a nit?

Nit is the scientific name for “empty shell” but is used interchangeably for egg. They are visible to the naked eye as soon as they are laid and remain the same size. They do not move or reattach once removed form the hair.

How many eggs/nits can a head louse lay in a day?

A single female louse lays eggs twice a day and approximately 4 to 5 eggs each time. Multiply that by 10, 20 or even 40 or more lice that might be on the head and it's easy to see how a severe infestation can develop quickly.

How do I know if a nit is viable?

The only way to be certain if an egg is viable is to look at it under a microscope.

Is it true that nits closest to the scalp are alive while those away from the scalp are dead?

Viable eggs can be found all over the hair shaft. While eggs are normally found close to the scalp it is because it's the perfect incubator. You can comb viable eggs down the hair shaft, especially when treating. It is never a good idea to assume eggs found further that 1/4 inch away from the scalp are dead.

How are lice spread? How do you get lice?

Head lice are spread through head-to-head contact. It's believed that less than 2% of active cases come from shared items. That is why communication with those individuals that you've had recent contact with is so important.

Do head lice carry disease?

Since head lice have a low morbidity rate and usually stay on one host their whole lives, the odds are low that they can spread disease. However, impetigo and other secondary infections due to scratching can occur. Some researchers believe that they carry diseases and studies are being done in that area to prove it.

When head lice transfer from one head to another, how soon can they start laying eggs?

If the head lice are fertilized females, they may begin laying eggs immediately. Head lice generally travel in harems, often consisting of seven or eight adult females and one adult male. As females will lay approximately 8 to 10 eggs daily, a simple case of head lice can escalate very quickly.

Are head lice able to fly or jump onto my child’s head?

No. Head lice do not jump or fly; they do not have jointed legs or wings. They can however move quickly on hair strands around 9 inches per minute! Off the hair they are slow and clumsy.

How long do head lice live?

A head louse can live on a person’s head approximately 30 days from hatched nymph to adult. They are not able to survive more than 24 hours off the head because they must feed every 3-4 hours. An egg, separated from the head, will die. It needs the warmth of the body to incubate (much like a chicken sitting on an egg).

Is there a head lice season?

It seems that there are more cases of head lice during the school months; this is not because of a lice season. When children have more contact with each other, we see an increase in numbers. Many schools also enforce head lice policies, thereby increasing awareness of the problem.

Is it possible to get head lice from our pet, or give it to our pet?

There are well over 3000 species of lice and they are all host specific meaning they cannot be transmitted to host of a different species. Humans get three sub species of lice: Head lice, Body lice and Pubic lice. Pets have their own lice.

Since head lice are not life threatening, why be concerned?

Head lice are highly contagious. If we don't rid ourselves of them, we may spread them to everyone around us. An infestation may lead to infections and other illnesses, behavioral issues, negative stigmas and rarely, injury and/or death.

Who is at risk of getting head lice?

Everyone with human blood is at risk. If you have contact with an infected person, you can get them.

Does race or ethnicity matter in contracting head lice?

Anyone, including African Americans, can get head lice. They are not as prevalent because of the shape of their individual hair strands but they are far from immune.

Do lice prefer a certain blood type?

Head lice will feed on any blood type, but some blood types are more attractive than others. Once they begin feeding on a certain type, they need the same blood type to survive. Studies conducted by Terry Meiking, research assistant professor, Department of Dermatology and Cutaneous Surgery at the University of Miami, found that head lice intentionally avoid an incompatible blood type (especially where the Rh factor is different) unless they were starving. When a louse consumes another blood type, it's intestinal tract explodes. But if the louse laid nits prior to feeding the nymphs that hatch can safely feed on the new blood type.

Are head lice more prevalent in warmer climates?

No. The only difference a warmer climate makes is the lice are more apt to move up and down the hair shaft and lay eggs throughout the hair, while in colder climates, they generally stay closer to the scalp.

Why do some people get head lice repeatedly while others never do?

There are many reasons why some people seem to get lice repeatedly. They may have not eradicated the first outbreak completely. If they are going back around the same people they got it from origanally and those people dont treat, re-infestation can occur. Studies have shown that head lice leave a scent that is attractive to other head lice and this is one reason to be extra diligent in rechecking and using prevention measures for 3 months or longer after the outbreak.

What can I do to prevent a case of head lice?

Keeping long hair pulled back or up in tight buns or braids is extremely important. Hair strands act as a bridge for head lice to move from one head to another. If a child has contact with a person who has an active case, take extra care in checking his or her head. Additional measures include applying a mint spray and running a good lice comb through the hair once a week are also great preventative measures.

What are the symptoms of head lice?

Symptoms can take 24 hours to 2 weeks to show up.
​Itching (only 50% of the population itches)
Swollen glands
Fidgety behavior
Sleepiness after a good night's rest
A rash at the back of the neck
Impetigo
Anemia (rare)
Hair loss (rare)

Is it true that you should never share a hat or comb?

Head lice cannot lice away from a human head and do not survive for more than 24 hours though they are too dehydrated to feed after 8-12, but sharing hats, helmets, and combs is never a good idea.

Can using hairspray prevent head lice?

Some people believe that lice won’t attach to dirty hair, so they overuse hairspray and gels. Using these products will not prevent or get rid of head lice.

Is there any way to ensure never getting a case of head lice?

Sadly no. Lice feed on blood; we are all potential hosts for head lice. That's why it is so important to always exercise proactive measures.

Won’t shaving my child’s head solve the problem?

Yes, but how many children want shiny bald heads? Shaving to rid lice does not mean the hair is cut short, it means shaving away all the hair on the head. Buzz cuts do not necessarily get rid of all lice or their eggs as head lice can grasp on very short lengths of hair.

How do I know if my child has head lice?

Check your child’s head on a regular basis and run a lice comb through the hair once or twice a week when you are made aware of an outbreak in your surroundings. Be aware of your child's behavior and watch for telltale signs. Click here to identify head lice and things mistaken for them.

Is it true that itching is the first sign of head lice?

Itching is caused by an allergic reaction to the scent in the saliva that head lice secrete when feeding. The saliva also keeps the blood from clotting, making the feeding process easier. About half of those who get head lice are not allergic to the saliva and therefore don’t itch. Even if someone is allergic, it can take approximately twenty four hours to four weeks for saliva build up to cause itching.

How long can a person have a case of head lice before realizing it?

It is possible to have head lice for years without knowing it, especially if the person does not experience itching. Generally, by the time someone identifies head lice, he/she has had head lice for three to eight weeks.

What is a cryptic infestation?

Occasionally a person believes that he or she has lice, even though none can be detected. The problem could be a biting insect or mite that is not present at the time of examination. Insects like mosquitoes, fleas, or bedbugs can bite and then leave. Hair care and laundry products, industrial fibers, an undiagnosed disease, anti-louse treatments or a person’s imagination can cause itching and irritation.

Does a case of head lice ever go away without intervention?

Lice nearly always continue to multiply and to spread to others. Only on a rare occasion would a case of head lice go away by itself (e.g. one unfertilized female or a lone male transfer to a head or all lice transferring to another head).

What is the quickest way to get past a case of head lice?

There is no shortcut. Tedious, time-consuming nitpicking and checking everyone with whom the person has had contact with is the first step toward eliminating head lice. A good comb (when used properly) can eliminate up to 85 percent of the problem. Even when you think you have done the job right, don't let your guard down. The life cycle of lice is approximately three weeks from egg to adult, so keep checking during that time period.

What should I do if I find head lice on my child?

Call your local professional or if you choose to do it yourself, start treating your child as swiftly as possible. The sooner treatment begins, the less the chance of it escalating or spreading to others. Check family members to make sure the lice haven’t yet spread. Only treat those who have head lice as treatment is not a preventative. Call the school, your child’s friends’ parents and others he or she has been in close contact with. Don’t be embarrassed. Instead, act fast to stop the spread.

If a child has head lice, should the whole family be treated?

If one family member has a cold, do you give medicine to everyone? Of course not! What you would do, however, is exercise precautionary measures. The same holds true with lice. Be aware, check, comb, and only if necessary, treat. You can always go to a professional lice removal service to confirm head lice.

What “DIY” treatment options are available for my family?

Many safe, non-toxic treatment options are available. If you could use only one tool or product, we would recommend a good metal lice comb. The most important thing is that you do something, as head lice left unattended will only escalate and spread to others. Check out the section on this site, DIY lice removal. In addition, here is a "before you treat check list."

What types of products should I look for when shopping?

Get a good metal lice comb. Look for safe, non-toxic, pesticide free products. Products alone will not eradicate head lice and nothing but removal kills all the eggs. Products are a means of augmenting the tedious task of nit removal. ​​Check out our page on product help.

Do home remedies work?

There are many home remedies, but in most situations we don't encourage their use. Most are messy and time-consuming and are no more effective than the safe products available today. In the end, it all comes down to nit removal.

Does putting mayonnaise on your head work?

Mayonnaise, petroleum jelly, olive oil, vinegar and other remedies are messy alternatives for treating head lice. The goal of these treatments is to drown the lice. Because lice can survive for many hours fully submerged in liquids, including those meant to kill them, these treatments are not very effective.

Why didn’t the products we bought at the pharmacy work?

Many products available today have been on the market a long time. Because of the span of time they’ve been used and overused, lice have built up resistance. Head lice are now 90-100% resistant to OTC products with pesticides, including some prescriptions with pesticides. Our children however have no resistance to the risks and side effects these dangerous chemicals pose.

Should I retreat?

If you treated using any pesticide containing product do not treat again. Instead keep looking and combing. The fact that you found more nits does not mean that there is a new case. It could be nothing more than missed nits. Observe not only how many you find, but whether they are scattered or clustered.

If you are finding nits in a quarter sized grouping you need to comb more and look harder. If they are scattered (for example, one behind the ear, one in bangs, and one at nape of neck) then most likely these nits were missed.

Keep looking and combing every two to three days. If you find a nit, pull it out and keep checking. Incorporate combing into your regular routine and spend five-ten minutes on clean detangled hair combing once a week!

I've heard the worst part of having head lice is all the cleaning. Is this true?

Cleaning is overemphasized. The parent's time is better spent on the child's head, as well as communicating with the child’s closest friends.

How much cleaning is necessary when my child has head lice?

Concentrate only on items that had direct contact with individuals suffering from head lice during the past 24 hours. There is only a small risk of a bug ending up off the head and it is usually injured or dying.

  • Change bedding
  • Throw a sheet over the couch for 24 hours
  • Pillows and stuffed animals can be put in dryer on high heat for 30 minutes.
  • Hairbrushes and accessories can go in the freezer overnight.​
  • Lint roll the headrest of the seats your child has used in vehicle.
  • ​Then Relax! No dry cleaning, bagging or burning down the house needed!
Does having head lice mean that a person lives in a dirty home or has poor hygiene?

Absolutely not! Getting a case of lice has nothing to do with the cleanliness of one's home or body. Head lice are spread by head to head contact. They do not live away from the head, so whether a house is clean or dirty makes no difference.

Do head lice prefer clean or dirty hair?

Head lice find it easier to move around on a clean head of hair; however, that does not mean that an individual with dirty hair won't get lice; they just stay closer to the scalp. Head lice feed on human blood and, if we have blood, we are at risk.

I'm shrinking our clothes by washing them with hot water and putting them in the dryer. Is there a better way to kill any lice that might be in our clothing?

Head lice cannot survive off the human head for more than 24 hours and they do not live on clothing. Dirty clothes worn by those with head lice can be washed in cold water and then dried on high heat for 30 minutes or a lower heat setting for an hour.​​​

Whom should I notify if my child has lice?

Everyone who has had contact with the child in at least the last 2 weeks, and preferably during the past month, should be notified. Contacts should include the school, child care director, camp counselor, or other individuals in the position to assist you in notifying and checking those that your child has had contact with. Be nice and tell on lice!!

How can I get my child's school more involved in this health issue?

Talk to the school principal,school nurse and your child's teachers. Address your concerns calmly and let them know that fighting head lice is a shared responsibility. Stress that the goal is not to place blame, but rather to work with them to help develop proactive measures to ensure that students remain lice free.


*Adapted from Canada's Nitwits lice removal team FAQ and information from the Shepherd Institute for Lice Solutions

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